Which term refers to valves, gauges, and devices used for regulation in engineering?

The term used to describe valves, gauges, and devices utilized for regulation in engineering is "instruments." Instruments are critical components within engineering systems as they are specifically designed for measuring, controlling, and indicating various parameters such as pressure, temperature, flow rate, and level. They play an essential role in monitoring system performance and ensuring safe and efficient operation.

Instruments are often part of a larger control system, enabling operators to make informed decisions based on real-time data. For example, a pressure gauge provides immediate feedback on the pressure level in a system, allowing for adjustments to be made to maintain safety and performance standards.

The other options do not accurately capture the specific role of valves, gauges, and regulation devices. "Components" is a broad category that encompasses any part of a system but lacks the specificity of indicating functionality. "Fittings" generally refer to parts used to connect pipes and tubes in plumbing or piping systems, rather than instruments that measure or control. "Connections" refers specifically to linkages between components, which does not address the regulatory functionality that instruments provide. Thus, "instruments" is the most appropriate term for this context.